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Comment by chm | Hacker News Reader

  A nation's newest war ship is slowly disappearing. The ship's hull
  is made of Aluminium while its cannon bores are made of Stainless Steel.
  What is happening, why, and how do you stop it?

Grad school chemistry/physics candicacy exam question, sure to generate colorful answers!

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'Galvanic corrosion' and applying a non-metalic layer between the cannon/deck would be my first thought. Now I'm curious as to some of the more 'colorful answers'.

Yes indeed: two different metals in electrical contact through an electrolyte solution (sea water). One way to stop this is to use a sacrificial anode (where the oxidation occurs) made of Magnesium, although this would probably be unpractical in salt water. A colorful answer would be to replace the water with a fluid like 3M's Fluorinert and replace the air with a nitrogen atmosphere. But that would also be unpractical.

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